CN1983459A - First wall component with ring segment - Google Patents

Abstract

The invention relates to a first wall element of a thermonuclear reactor comprising at least one heat shield of graphite material and cooling tubes of copper or copper alloy. A pipe section is arranged between the heat shield and the cooling pipe, and at least some areas of the pipe section are connected to the heat shield and the cooling pipe through a layer containing copper.

Description

first wall member with pipe segment

technical field

The invention relates to a first wall component of a thermonuclear reactor comprising at least one heat shield of graphite material and cooling tubes of copper or copper alloy, said heat shield having a closed or open duct.

Background technique

Typical examples of uses of such first wall members are diverters and limiters under extremely high thermal load conditions exceeding 10 MW/m ² . The first wall member typically includes a heat shield and a heat dissipation zone. Heat shield materials must be compatible with the plasma, have high resistance to physical and chemical sputtering, high melting/sublimation points and the highest possible resistance to thermal shock. In addition, it must have high thermal conductivity, low neutron activation and appropriate strength/fracture toughness, as well as good availability and acceptable cost. Apart from refractory metals such as tungsten, graphite materials best meet these varied and somewhat conflicting requirements. Such first wall components are usually effectively cooled due to the prolonged energy flow from the plasma acting on these components. Dissipation is dissipated by, for example, copper or copper alloy heat sinks, which are typically attached to the heat shield by a largely material bond.

Copper has the function of ensuring heat dissipation. In addition, graphite also performs a stress-reducing function when it is bonded to high-strength copper alloys through a copper interlayer (such as copper-chromium-zirconium). In this case, the copper layer typically has a thickness of 0.5 to 3 mm.

In addition to graphite and one or more regions of copper material, such a first wall member may also comprise other regions, such as steel or tungsten alloys.

In this case, the connection zone between graphite and copper shows the weakness of this composite material. EP 0 663 670 B1 describes a method for producing a cooling device with improved strength in the connection zone. Where the molten metal of the cooling device is in contact with the heat-resistant material, the joining zone is provided with one or more metal elements of groups IV and/or V of the periodic table during the joining operation. The composite material thus produced has greatly improved strength.

The first wall member can be made of different designs. Here, a distinction is drawn between flat, saddle and monolithic designs.

If a heat shield with a flat connection surface is connected to a cooling fin through which the coolant flows, this is referred to as a flat tile design. In a saddle design, a heat shield with a semi-circular groove connects to a tubular heat sink. In each design, the heat sink has the function of forming a thermal contact between the heat input side and the cooling medium, and is thus exposed to cyclic, thermally induced in the load. In a monolithic design, the first wall member comprises a heat shield with concentric ducts. The heat shield is connected to the cooling pipe through the concentric pipe.

Due to the geometrical conditions, the stress reduction induced by the plastic deformation of the copper interlayer occurs more efficiently in the flat tile-like design than in the monolithic design where the three-dimensional stress state exists, which minimizes the plastic deformation. Due to this confined stress reduction, cracks develop in the graphite material.

The first wall component has to withstand not only thermally induced mechanical stresses, but also additionally occurring mechanical stresses. This additional mechanical load can be generated by electromagnetically induced currents flowing into the component and interacting with the surrounding magnetic field. This may involve the presence of high frequency acceleration forces, which must be transmitted by the heat shield. However, graphite materials have low mechanical strength and fracture toughness. In addition, neutron embrittlement, which occurs during use, causes a further increase in the sensitivity of these materials, leading to the occurrence of cracks.

Fiber-reinforced graphite (CFC) is generally used as the graphite material. Here, the fiber implementation is three-dimensionally and linearly arranged. Depending on the spatial orientation, the architecture of this fiber can provide materials with different properties. Typically, CFC is reinforced in one spatial direction by ex-pitch fibers, which have the best combination of strength and thermal conductivity. The other two spatial directions are reinforced by pre-PAN fibers, usually only one direction is needled.

Thus, while the CFC has an architecture of linear materials, the geometry of the heat shield/cooling tube connection is circular to a monolithic design. Due to the different coefficients of thermal expansion of the materials used, a build-up of stress occurs during the production process and this stress can lead to cracks in the CFC.

Due to the geometry of the composite materials used, these cracks, if any, can only be detected with very complex methods. Against the background of the nuclear radiation environment of such components, it raises corresponding problems, especially since cracks/detachment can be considered as a possible cause of more serious events.

Despite many years of intensive research work in the field of first wall elements, the structural elements available hitherto do not meet the requirements optimally.

Contents of the invention

It is therefore an object of the present invention to provide a first wall component of one-piece design which meets the requirements of mechanical and physical stress in an appropriate manner.

This object is achieved by the features of claim 1 .

The first wall member of the present invention comprises at least one heat shield of graphite material and a cooling pipe of copper or copper alloy, the heat shield has closed or open pipes, and a gap is arranged between the heat shield and the cooling pipe Pipe section. The pipe section is respectively connected with the heat shield and the cooling pipe through the ductile copper layer.

The pipe sections have the effect of reducing internal stresses in the heat shield due to the different expansion coefficients. In order to obtain this effect in an optimal manner, it is advantageous if the coefficients of expansion of the heat shield and the pipe section are similar, and the pipe section has a sufficient thickness of at least 0.2 mm, as well as the highest possible thermal conductivity and strength. If the thickness is small, sufficient pressure reduction cannot be achieved. Due to geometric conditions, the upper limit is about 1.5mm.

Materials that meet the mechanical/physical requirements of the pipe section well include molybdenum, molybdenum alloys, tungsten and tungsten alloys.

Particular attention should be paid to the false alloys in the tungsten-copper system and the molybdenum-copper system. For tungsten-copper, the preferred copper content is 5 to 25 wt%, and for molybdenum-copper, the preferred copper content is 15 to 40 wt%. The pipe section can have an opening angle α of 20° to 180°, preferably 50° to 130°. When the opening angle is large, the pressure drop is not sufficient. At smaller opening angles, heat flux is hindered.

Advantageously, the angle bisector of the opening angle α is perpendicular to the surface of the heat shield exposed to the plasma. The heat shield is connected via a copper-containing layer to the pipe section, which in turn is likewise connected to the cooling pipe via a copper-containing layer. These layers also function as stress reducers. The open area of the tube section is likewise filled with copper or copper alloy, so that in this area the heat shield is connected to the cooling tube via the copper-containing area. Thus, in this zone, the heat flux is not attenuated by the pipe section.

The ducts leading through the heat shield are preferably closed and formed with holes, the walls of which are laser-structured and activated metallically and/or carbonized.

To manufacture the first wall element of the invention, first a duct, preferably a hole, is introduced into a block of graphite material, preferably CFC. The pipe surface is preferably structured by laser and subsequently activated metallically and/or carbonized in such a way that the activated surface is wettable by liquid copper. The pipe section is then inserted into the pipe preconditioned in this way. In the present invention, the preferred thickness of the pipe section is 0.2 to about 1.5 mm. The gap between the pipe section and the wall of the activation duct is about 0.2 to 0.8 mm. A copper sleeve is introduced into the gap. And the red copper sleeve is set against the inner diameter of the pipe section. The configuration produced in this way is heated to a temperature above the melting point of copper under vacuum or inert gas. To ensure copper replenishment, especially in CFC, a corresponding copper reservoir is provided in the gap between the pipe section and the open area of the pipe section.

This produces a composite with the following radial configuration (from outside to inside): CFC/active layer/copper/molybdenum-copper or tungsten-copper/copper.

Copper alloy cooling tubes, preferably copper-chromium-zirconium cooling tubes, can be largely bonded to the inner copper layer by commonly used standard methods such as welding or HIP processes.

Description of drawings

Figure 1 is an oblique perspective view of a first wall member of the present invention.

Fig. 2 is a front view of the first wall member of the present invention as shown in Fig. 1 .

Figure 3 is an oblique projection of the pipe section.

Detailed ways

The present invention is described in detail below by way of examples.

The first wall member 1 was manufactured using a CFC heat shield 2 measuring 45mm x 30mm x 25mm. The CFC heat shield 2 has a three-dimensional fiber structure, giving different properties depending on the direction. The fibers with the highest thermal conductivity are arranged parallel to the outer dimension of 45 mm. The fiber bundles with average thermal conductivity are arranged parallel to the outer dimension of 30 mm. At its center of symmetry, a through-hole 4 with a diameter of 18 mm is introduced vertically into an area of 30 mm×45 mm. This 25 mm deep hole was subsequently laser structured, achieving an increase in surface area of over 100%. The conical laser hole has a depth of about 1000 μm and an open width of about 200 μm on the surface. In this embodiment, the laser pulse sequence is selected such that the individual holes are arranged as close as possible. The surface treated in this way is activated, so that a carbonized bonding surface wetted by liquid copper is produced on the CFC material 2 . This is achieved by titanium coating the surface. The part is then heated to a temperature above the melting point of titanium, and due to capillary forces, the molten titanium infiltrates the CFC, forming titanium carbide. Titanium carbide on the one hand adheres to the CFC with good chemistry and on the other hand makes the heat shield 2 wettable for liquid copper. Then, a copper sheet with a thickness of 0.4 mm is placed in the activation hole 4 in such a way that a cylinder is formed, which is positioned against the inside of the hole in the heat shield 2 . Subsequently, a tungsten pipe section 5 with a copper content of 10% by weight and a height of 25 mm, an outer diameter of 17 mm, a wall thickness of 0.5 mm and an opening angle α of 90° is introduced into the hole. In this embodiment, the angle bisector of the opening angle α is vertically set on the area of 45mm×25mm. During use, this area 9 is in contact with the plasma. A copper core with an outer diameter of 15.8 mm is arranged in the inner region of the pipe section 5, which core has a front end with a diameter of 20 mm. The function of this front end is the Fusion library. The assembly was then placed in a vacuum furnace and heated under vacuum to 1100° C. for about 10 minutes before being introduced into a cooling stage.

In this way, the heat shield 2 is connected to the pipe section 5 via the copper layer 6 . The open area 8 of the pipe section 5 is likewise filled with copper. Subsequently, the monolithic cylinder blocks produced in this way work in all respects. In each case the original external dimensions were thus reduced by 1mm, so that before further machining the integral cylinder block had external dimensions of 44mm x 29mm x 24mm. The copper filled pipe 4 was drilled to a diameter of 15 mm. In this embodiment, the inner diameter has a continuous copper layer 7 . A copper-chromium-zirconium tube 3 with an outer diameter of 14.8 mm is then placed in the pipe 4 . Subsequently, the cooling tube 3 and the integral cylinder block are bonded to a large extent by the HIP process, thus resulting in an effectively coolable first wall element 1 .

Claims (13)

1. A first wall element (1) of a thermonuclear reactor comprising at least one heat shield (2) of graphite material and cooling tubes (3) of copper or copper alloy, said heat shield (2) having a closed or open The pipe (4) is characterized in that a pipe section (5) is arranged between the heat shield (2) and the cooling pipe (3), and at least some areas of the pipe section (5) pass through the copper-containing layer (6 , 7) are connected with heat shield plate (2) and cooling pipe (3). 2. The first wall element (1) according to claim 1, characterized in that the pipe section (5) has an opening angle α of 20 to 180°. 3. The first wall element (1 ) according to claim 2, characterized in that said opening angle a of said pipe section (5) is 50° to 130°. 4. The first wall element (1) according to any one of claims 1 to 3, characterized in that the angle bisector of the opening angle α is perpendicular to the surface of the heat shield (2) in contact with the plasma (9). 5. The first wall element (1 ) according to any one of claims 1 to 4, characterized in that the wall thickness of the pipe section (5) is 0.2 to 1.5 mm. 6. The first wall element (1) according to any one of claims 1 to 5, characterized in that the heat shield (2) is connected to the cooling area (8) of the pipe section (5) through the copper-containing area Tube (3) is connected. 7. The first wall member (1) according to any one of claims 1 to 6, characterized in that the material constituting the pipe section (5) includes molybdenum, molybdenum alloys, tungsten and tungsten alloys. 8. The first wall element (1 ) according to claim 7, characterized in that the pipe section (5) consists of molybdenum-copper or tungsten-copper. 9. The first wall element (1 ) according to any one of claims 1 to 8, characterized in that the heat shield (2) consists of CFC. 10. The first wall element (1 ) according to any one of claims 1 to 9, characterized in that the cooling tube (3) consists of copper-chromium-zirconium. 11. A first wall element (1) according to any one of claims 1 to 10, characterized in that said duct (4) is a hole. 12. The first wall element (1) according to any one of claims 1 to 11, characterized in that the duct (4) is constructed by laser. 13. The first wall element (1 ) according to any one of claims 1 to 12, characterized in that at least some regions of the wall of the duct (4) have a layer of titanium carbide.